Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in CPP):

Solution:
#include<bits/stdc++.h>
using namespace std;
#define pii pair<int,int>
int dx[4] = {1,0,-1,0};
int dy[4] = {0,1,0,-1};

int main(){
	int H,W;
	cin >> H >> W;
	string S[110];
	int dist[110][110];
	int wsum = 0;
	for(int i=0;i<H;i++){
		cin >> S[i];
		for(int j=0;j<W;j++){
			if(S[i][j]=='.') wsum++;
		}
	}
	memset(dist, -1, sizeof(dist));
	dist[0][0] = 1;
	queue<pii> que;
	que.push(make_pair(0, 0));
	while(!que.empty()){
		pii cur = que.front();que.pop();
		int x = cur.first, y = cur.second;
		for(int dir=0;dir<4;dir++){
			int nx = x + dx[dir], ny = y + dy[dir];
			if(nx<0 || nx >= H || ny < 0 || ny >= W) continue;
			if(S[nx][ny]=='#') continue;
			if(dist[nx][ny] == -1){
				dist[nx][ny] = dist[x][y] + 1;
				que.push(pii(nx, ny));
			}
		}
	}

	if(dist[H-1][W-1] == -1) cout << -1 << endl;
	else cout << wsum - dist[H-1][W-1] << endl;
}